BRITISH AIRWAYS hopes to slash the cost of implementing US Federal Aviation Administration airworthiness directives (ADs) concerning the formation of "blue ice" on aircraft, with the introduction of a testing device developed by Aaxico Industries of the UK.
The FAA ADs, which initially apply to the McDonnell Douglas DC-10 and Boeing 727, require that toilet-drain and flush-fill valves are regularly tested for any leakage of sewage.
Blue ice forms when leaking fluid freezes at cruising altitude, breaking off in lumps as the ambient temperature rises during descent. This poses a safety hazard to the aircraft's structure and engines, and people and property on the ground.
Aaxico's Blister (blue-ice tester) is designed to eliminate the expensive need to pressurise aircraft on the ground to check for leaks. The Blister uses a vacuum pump to simulate ground pressurisation, subjecting the toilet-drain and flush-fill valves to a vacuum pressure of 255mmHg. If the vacuum pressure holds, the valves can be deemed to be leak-free.
"The official testing procedure is an onerous task, implying ground pressurisation of the aircraft by running the engines or auxiliary power unit," says Ron Wheeler, Aaxico operations director.
Source: Flight International
